Apparatuses with appropriately high resolution are required for detection of magnetic fields with a low field strength. Conventional apparatuses admittedly achieve the necessary resolution, but problems occur as soon as there are interfering electromagnetic fields in the vicinity.
The required resolution is admittedly achieved by the use of SQUID sensors (SQUID=Superconduction Quantum Interference Device), but problems occur in the event of interference caused by electromagnetic fields in the vicinity. Furthermore, the SQUID sensors have antenna elements composed of superconducting material. These require cooling, which increases the design complexity.
The use of a spin magnetometer likewise provides the required resolution, but a supporting magnetic field with a relatively high field strength is required. Furthermore, the supporting field must be very stable over time. The spin magnetometer has numerous components, so that the design complexity is relatively high. Furthermore, a spin magnetometer cannot be designed as an integrated circuit.
Finally, apparatuses with magnetoresistive sensors (XMR sensors) are known, whose resistance value depends on the field strength of the magnetic field. XMR sensors likewise achieve, strength of the magnetic field. XMR sensors likewise achieve, for example, the required resolution, but are susceptible to interference from electromagnetic fields in the vicinity. Shielding devices would considerably increase the design complexity.